"People are devastated by what's happening and we're trying to be that sympathetic understanding that ... we know where you're coming from, you want to be in your home," said Sgt. Rob Marsollier. "However, of course, safety is paramount with us, making sure everybody is in and out as quick as possible."

Nicholas Steadfast had to flee his home in a trailer park adjacent to the Hangingstone River and ended up at an arena where he stayed the night.

"It feels like some freedom has been taken away," he said. "That's where I reside, where I've been residing for the last two years. I'm happy I was able to take out personal belongings and get stuff out the night before, but I feel ... a little bit stressed."

Resident James Kollmar, volunteering to help fill sandbags at the arena, said if nothing else the flood is bringing the town together as a community.

"It's interesting to see everybody that's willing to help out, (who) take time out of their day to help anybody out, offering places to stay."

River dangerously high

Days of heavy rain have pushed local waterways, particularly the Hangingstone River, to dangerously high levels, officials said. Some neighbourhoods are under boil-water advisories, and people in the flood zone are waiting for the knock at the door to tell them to get out.

"Like panic attack packing, it's like grab everything, what's important and what's not, because if they start knocking on the door, we have 10 minutes to get out of here," resident Katharina Durand told CBC News.

Fire Chief Darby Allen, of the regional municipality of Wood Buffalo, said 151 people had voluntarily left their homes. He said he has never seen flooding like this in Fort McMurray.

"It's actually calmed down a little bit overnight, but the last 36 hours or so have been fairly hectic," he told CBC's Heather Hiscox.

"We've never seen water levels like it here for as long as they've kept records, that the Hangingstone is the highest it's ever been, and obviously … that's created some challenges, and caused damage to the river banks, large erosion, roads have gone, pathways have gone, electrical power poles have fallen in the river. It's been — it's been quite the ride."

He said police and firefighters can issue mandatory evacuation orders, given the state of emergency, but so far only recommendations have been made.

"If we get to a situation where we feel that lives are in danger … in that case we will evacuate the people, whether they want to or not. "

20 choose to stay

As of Wednesday morning, 151 people had left their homes, and about 20 had chosen to stay where they are.

Evacuees are being taken to a local sports arena. Some have found accommodation with family or friends, Allen said.

On Tuesday, the mayor of Fort McMurray declared a local state of emergency over flooding caused by Hangingstone River overrunning its banks and concerns that the Clearwater River will add to the flooding. (CBC)

At dawn today, officials planned to evaluate the state of river erosion, especially a nearby trailer court.

"We've had some issues with power and gas lines, so that's on our priority," Allen said.

Rain is forecast to continue Wednesday in Fort McMurray, with a risk of a thunderstorm in the afternoon, with as much as 10 millimetres expected.

On Tuesday, the mayor of Fort McMurray declared a local state of emergency over flooding caused by Hangingstone River overrunning its banks and concerns that the Clearwater River will also flood.

"The state of local emergency is being declared for public safety reasons," Melissa Blake, mayor of the Regional Municipality of Wood Buffalo, said at a council meeting.